Implement <resize><drawContents>

<resize><drawContents>[yes|no] configures whether to let the clients
redraw its window content content while resizing.

When <resize><drawContents> is set to no, a multi-rect is shown to
indicate the geometry of the resized window.

docs/labwc-config.5.scd

@@ -456,6 +456,11 @@ extending outward from the snapped edge.
 
 	Default is Never.
 
+*<resize><drawContents>* [yes|no]
+	Let the application redraw its contents while resizing. If disabled, an
+	outlined rectangle is shown to indicate the geometry of resized window.
+	Default is yes.
+
 ## KEYBOARD
 
 *<keyboard><numlock>* [on|off]

docs/rc.xml.all

@@ -103,8 +103,12 @@
     <windowEdgeStrength>20</windowEdgeStrength>
   </resistance>
 
-  <!-- Show a simple resize and move indicator -->
-  <resize popupShow="Never" />
+  <resize>
+    <!-- Show a simple resize and move indicator -->
+    <popupShow>Never</popupShow>
+    <!-- Let client redraw its contents while resizing -->
+    <drawContents>yes</drawContents>
+  </resize>
 
   <focus>
     <followMouse>no</followMouse>

include/config/rcxml.h

@@ -118,6 +118,7 @@ struct rcxml {
 	enum tiling_events_mode snap_tiling_events_mode;
 
 	enum resize_indicator_mode resize_indicator;
+	bool resize_draw_contents;
 
 	struct {
 		int popuptime;

include/resize-outlines.h

@@ -0,0 +1,13 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+#ifndef LABWC_RESIZE_OUTLINES_H
+#define LABWC_RESIZE_OUTLINES_H
+
+#include <wlr/util/box.h>
+
+struct view;
+
+void resize_outlines_update(struct view *view, struct wlr_box new_geo);
+void resize_outlines_finish(struct view *view);
+bool resize_outlines_enabled(struct view *view);
+
+#endif /* LABWC_RESIZE_OUTLINES_H */

include/view.h

@@ -238,6 +238,10 @@ struct view {
 		struct wlr_scene_rect *background;
 		struct scaled_font_buffer *text;
 	} resize_indicator;
+	struct resize_outlines {
+		struct wlr_box view_geo;
+		struct multi_rect *rect;
+	} resize_outlines;
 
 	struct foreign_toplevel {
 		struct wlr_foreign_toplevel_handle_v1 *handle;

src/config/rcxml.c

@@ -1032,6 +1032,8 @@ entry(xmlNode *node, char *nodename, char *content)
 		} else {
 			wlr_log(WLR_ERROR, "Invalid value for <resize popupShow />");
 		}
+	} else if (!strcasecmp(nodename, "drawContents.resize")) {
+		set_bool(content, &rc.resize_draw_contents);
 	} else if (!strcasecmp(nodename, "mouseEmulation.tablet")) {
 		set_bool(content, &rc.tablet.force_mouse_emulation);
 	} else if (!strcasecmp(nodename, "mapToOutput.tablet")) {
@@ -1271,6 +1273,7 @@ rcxml_init(void)
 		| LAB_VIEW_CRITERIA_NO_SKIP_WINDOW_SWITCHER;
 
 	rc.resize_indicator = LAB_RESIZE_INDICATOR_NEVER;
+	rc.resize_draw_contents = true;
 
 	rc.workspace_config.popuptime = INT_MIN;
 	rc.workspace_config.min_nr_workspaces = 1;

src/input/cursor.c

@@ -24,6 +24,7 @@
 #include "menu/menu.h"
 #include "regions.h"
 #include "resistance.h"
+#include "resize-outlines.h"
 #include "ssd.h"
 #include "view.h"
 #include "xwayland.h"
@@ -306,7 +307,11 @@ process_cursor_resize(struct server *server, uint32_t time)
 			server->grab_box.width - new_view_geo.width;
 	}
 
-	view_move_resize(view, new_view_geo);
+	if (rc.resize_draw_contents) {
+		view_move_resize(view, new_view_geo);
+	} else {
+		resize_outlines_update(view, new_view_geo);
+	}
 }
 
 void
@@ -1134,6 +1139,9 @@ cursor_finish_button_release(struct seat *seat)
 
 	if (server->input_mode == LAB_INPUT_STATE_MOVE
 			|| server->input_mode == LAB_INPUT_STATE_RESIZE) {
+		if (resize_outlines_enabled(server->grabbed_view)) {
+			resize_outlines_finish(server->grabbed_view);
+		}
 		/* Exit interactive move/resize mode */
 		interactive_finish(server->grabbed_view);
 		return true;

src/meson.build

@@ -20,6 +20,7 @@ labwc_sources = files(
   'placement.c',
   'regions.c',
   'resistance.c',
+  'resize-outlines.c',
   'seat.c',
   'server.c',
   'session-lock.c',

src/resize-outlines.c

@@ -0,0 +1,56 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#include <wlr/types/wlr_scene.h>
+#include "common/graphic-helpers.h"
+#include "ssd.h"
+#include "resize-outlines.h"
+#include "labwc.h"
+
+bool
+resize_outlines_enabled(struct view *view)
+{
+	return view->resize_outlines.rect
+		&& view->resize_outlines.rect->tree->node.enabled;
+}
+
+void
+resize_outlines_update(struct view *view, struct wlr_box new_geo)
+{
+	struct resize_outlines *outlines = &view->resize_outlines;
+
+	if (!outlines->rect) {
+		float *colors[3] = {
+			view->server->theme->osd_bg_color,
+			view->server->theme->osd_label_text_color,
+			view->server->theme->osd_bg_color,
+		};
+		int width = 1;
+		outlines->rect = multi_rect_create(
+			view->scene_tree, colors, width);
+	}
+
+	struct border margin = ssd_get_margin(view->ssd);
+	struct wlr_box box = {
+		.x = new_geo.x - margin.left,
+		.y = new_geo.y - margin.top,
+		.width = new_geo.width + margin.left + margin.right,
+		.height = new_geo.height + margin.top + margin.bottom,
+	};
+	multi_rect_set_size(outlines->rect, box.width, box.height);
+	wlr_scene_node_set_position(&outlines->rect->tree->node,
+		box.x - view->current.x, box.y - view->current.y);
+	wlr_scene_node_set_enabled(
+		&view->resize_outlines.rect->tree->node, true);
+
+	outlines->view_geo = new_geo;
+
+	resize_indicator_update(view);
+}
+
+void
+resize_outlines_finish(struct view *view)
+{
+	view_move_resize(view, view->resize_outlines.view_geo);
+	wlr_scene_node_set_enabled(
+		&view->resize_outlines.rect->tree->node, false);
+}

src/ssd/resize-indicator.c

@@ -7,6 +7,7 @@
 #include "common/scaled-font-buffer.h"
 #include "labwc.h"
 #include "resize-indicator.h"
+#include "resize-outlines.h"
 #include "view.h"
 
 static void
@@ -159,25 +160,30 @@ resize_indicator_update(struct view *view)
 
 	char text[32]; /* 12345 x 12345 would be 13 chars + 1 null byte */
 
-	int eff_height = view_effective_height(view, /* use_pending */ false);
-	int eff_width = view->current.width;
+	struct wlr_box view_box;
+	if (resize_outlines_enabled(view)) {
+		view_box = view->resize_outlines.view_geo;
+	} else {
+		view_box = view->current;
+		view_box.height = view_effective_height(view, /* use_pending */ false);
+	}
 
 	switch (view->server->input_mode) {
 	case LAB_INPUT_STATE_RESIZE:
 		; /* works around "a label can only be part of a statement" */
 		struct view_size_hints hints = view_get_size_hints(view);
 		snprintf(text, sizeof(text), "%d x %d",
-			MAX(0, eff_width - hints.base_width)
+			MAX(0, view_box.width - hints.base_width)
 				/ MAX(1, hints.width_inc),
-			MAX(0, eff_height - hints.base_height)
+			MAX(0, view_box.height - hints.base_height)
 				/ MAX(1, hints.height_inc));
 		break;
 	case LAB_INPUT_STATE_MOVE:
 		; /* works around "a label can only be part of a statement" */
 		struct border margin = ssd_get_margin(view->ssd);
 		snprintf(text, sizeof(text), "%d , %d",
-			view->current.x - margin.left,
-			view->current.y - margin.top);
+			view_box.x - margin.left,
+			view_box.y - margin.top);
 		break;
 	default:
 		wlr_log(WLR_ERROR, "Invalid input mode for indicator update %u",
@@ -194,9 +200,9 @@ resize_indicator_update(struct view *view)
 	resize_indicator_set_size(indicator, width);
 
 	/* Center the indicator in the window */
-	wlr_scene_node_set_position(&indicator->tree->node,
-		(eff_width - indicator->width) / 2,
-		(eff_height - indicator->height) / 2);
+	int x = view_box.x - view->current.x + (view_box.width - indicator->width) / 2;
+	int y = view_box.y - view->current.y + (view_box.height - indicator->height) / 2;
+	wlr_scene_node_set_position(&indicator->tree->node, x, y);
 
 	scaled_font_buffer_update(indicator->text, text, width, &rc.font_osd,
 		rc.theme->osd_label_text_color, rc.theme->osd_bg_color,